The present invention is directed to an absorbent product having at least a top layer, an absorbent core, and a breathable outer cover material. A fibrous nonwoven web having creped regions is disposed between the absorbent core and the breathable outer cover, causing a reduction in surface dampness on the outer surface of the breathable outer cover material when the absorbent core is wet without significantly reducing breathability of the outer cover when the absorbent core is dry.
Absorbent articles, such as diapers, child training pants, adult incontinence garments, swim wear and the like, typically include at least a liquid-permeable top layer for direct contact with the wearer, an absorbent core layer, and a substantially liquid-impermeable outer cover material. The absorbent core is positioned between the top layer and the outer cover material. When the absorbent article is exposed to a liquid insult, liquid passes through the top layer and into the absorbent core. The outer cover prevents the liquid in the absorbent core from leaving the garment.
Many of today""s absorbent garments utilize breathable outer cover materials. Breathable outer cover materials are substantially impermeable to liquids, but are permeable to water vapor. Breathable outer cover materials permit escape of water vapor from the absorbent garment, increasing the garment comfort and reducing skin rashes and other irritations that result when water vapor is trapped inside the garment and heated by the wearer""s body. Many of today""s absorbent garments are highly breathable, for maximum wearer comfort.
One shortcoming of breathable absorbent articles is a cold, damp, clammy feel that often occurs on the outside of the garment, i.e., on the outside of the outer cover material. This perceived surface dampness is caused when liquid water vaporizes from the absorbent core and passes through the microporous outer cover, removing heat from the diaper""s absorbent core via evaporative cooling. This in turn leaves the outer cover surface feeling cold and clammy, which is perceived by the consumer as damp. There is a need or desire in the absorbent garment industry for absorbent articles which are highly breathable, yet which reduce or avoid the perceived dampness caused by evaporative cooling.
The present invention is directed to an absorbent article having a breathable outer cover material and reduced perceived outer cover dampness. The absorbent article includes at least a liquid-permeable top layer, a breathable, substantially liquid impermeable outer cover material, and an absorbent core layer between the top layer and the outer cover material. The outer cover material may include a breathable film laminated to a nonwoven filament web, and may be positioned with the film facing inward (i.e., toward the absorbent core) and with the nonwoven web facing outward. In accordance with the invention, a second nonwoven filament web is interposed between the absorbent core and the breathable outer cover material. The second nonwoven web comprises a creped thermoplastic nonwoven web. Preferably, the creped nonwoven web has interfilament bonded areas which are bent or oriented permanently out-of-plane, unbonded areas between the bonded areas, and filament looping in the unbonded areas. Preferably, at least some of the filaments have hollow interiors.
The creped thermoplastic nonwoven web has a three-dimensional structure which traps a quantity or layer of air between the absorbent core and the outer cover. The air layer, partially encapsulated in the creped nonwoven web, insulates and slows heat transfer between the absorbent core and the outer cover. The evaporative cooling from a wet absorbent core is less readily transmitted to the outer cover, causing the outer surface of the outer cover to feel warmer and drier when touched.
Furthermore, the creped nonwoven layer provides paths for sideways diffusion and convection, facilitating the removal of moisture from the diaper, including moisture near the skin. This contributes to reduced skin hydration. Furthermore, the creped nonwoven layer, and the air within it, causes the diaper to have a resilient, soft, springy surface feel. Finally, the creped nonwoven filament web is permeable enough so as not to appreciably reduce moisture vapor transmission from the absorbent core through the outer cover material.
The creped thermoplastic nonwoven web may be composed wholly or partially of hollow thermoplastic filaments. The hollow filaments trap additional air, thereby increasing the insulative properties. Also, the hollow filaments lower the overall material cost and facilitate bulk and rigidity in the creped thermoplastic nonwoven web.
With the foregoing in mind, it is a feature and advantage of the invention to provide an absorbent article with a breathable outer cover system whose thermal conductivity is favorably decreased by the addition of a creped nonwoven web between the outer cover and absorbent core.
It is also a feature and advantage of the invention to provide a breathable absorbent article having a dampness-inhibiting layer which does not appreciably reduce breathability of the outer cover.
It is also a feature and advantage of the invention to provide an absorbent article having a breathable outer cover which remains warm and dry to the touch under a wide variety of conditions.
It is also a feature and advantage of the invention to provide an absorbent article having a resilient, soft, springy surface feel.